(i) Field of the Invention
This invention relates to novel .gamma.-butyrolactone derivatives, and more specifically to novel .gamma.-butyrolactone derivatives useful as antihypertensive drugs.
(ii) Description of the Prior Art
It has been known that compounds, which can either inhibit or suppress the conversion of angiotensin I into angiotensin II, are useful for the treatment of hypertension. A great deal of work has hence been carried out with respect to drugs having the above converting-enzyme inhibitory effects.
The above-mentioned effects have been reported to date in regard to numerous substances. For example, Japanese Patent Laid-Open No. 218596/1986 discloses to the effect that certain specific alkylaminofuranon derivatives are useful for the treatment of hypertension. The effects of these derivatives are however still insufficient. It has therefore been desired to develop novel drugs having still better effects for hypertension.